// Taken from PCRE pcre_stringpiece.h
//
// Copyright (c) 2005, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
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// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Author: Sanjay Ghemawat
//
// A string like object that points into another piece of memory.
// Useful for providing an interface that allows clients to easily
// pass in either a "const char*" or a "string".
//
// Arghh!  I wish C++ literals were automatically of type "string".

#ifndef MUDUO_BASE_STRINGPIECE_H
#define MUDUO_BASE_STRINGPIECE_H

#include <string.h> // 这个应该是c语言的string.h吧！
#include <iosfwd>    // for ostream forward-declaration

#include <muduo/base/Types.h>
#ifndef MUDUO_STD_STRING
#include <string> // 这玩意才是stl::string
#endif

namespace muduo {

// For passing C-style string argument to a function.
	class StringArg // copyable
	{
	public:
		StringArg(const char* str)
			: str_(str)
		{}

		StringArg(const string& str)
			: str_(str.c_str())
		{}

#ifndef MUDUO_STD_STRING
		StringArg(const std::string& str)
			: str_(str.c_str())
		{}
#endif

		const char* c_str() const { return str_; } // 好吧，无非是将自己封装的char* 暴露出去了而已

	private:
		const char* str_;
	};

	class StringPiece {
	private:
		const char*   ptr_; // 指针
		int           length_; // 长度

	public:
	 // We provide non-explicit singleton constructors so users can pass
	 // in a "const char*" or a "string" wherever a "StringPiece" is
	 // expected.
		StringPiece() // 默认的构造函数
			: ptr_(NULL)
			, length_(0) {}
		StringPiece(const char* str)
			: ptr_(str)
			, length_(static_cast<int>(strlen(ptr_))) {}
		StringPiece(const unsigned char* str) // 好诡异的写法
			: ptr_(reinterpret_cast<const char*>(str))
			, length_(static_cast<int>(strlen(ptr_))) {}
		StringPiece(const string& str) // 这个string类型代表的是stl的string?
			: ptr_(str.data())
			, length_(static_cast<int>(str.size())) {}
#ifndef MUDUO_STD_STRING
		StringPiece(const std::string& str)
			: ptr_(str.data())
			, length_(static_cast<int>(str.size())) {}
#endif
		StringPiece(const char* offset, int len)
			: ptr_(offset)
			, length_(len) {}

			  // data() may return a pointer to a buffer with embedded NULs, and the
			  // returned buffer may or may not be null terminated.  Therefore it is
			  // typically a mistake to pass data() to a routine that expects a NUL
			  // terminated string.  Use "as_string().c_str()" if you really need to do
			  // this.  Or better yet, change your routine so it does not rely on NUL
			  // termination.
		const char* data() const { return ptr_; } // 这个玩意好像stl的string啊
		int size() const { return length_; }
		bool empty() const { return length_ == 0; }
		const char* begin() const { return ptr_; }
		const char* end() const { return ptr_ + length_; } // 好吧，确实很漂亮

		void clear() { ptr_ = NULL; length_ = 0; }
		void set(const char* buffer, int len) { ptr_ = buffer; length_ = len; }
		void set(const char* str) {
			ptr_ = str;
			length_ = static_cast<int>(strlen(str));
		}
		void set(const void* buffer, int len) {
			ptr_ = reinterpret_cast<const char*>(buffer);
			length_ = len;
		}

		char operator[](int i) const { return ptr_[i]; }

		void remove_prefix(int n) {
			ptr_ += n;
			length_ -= n;
		}

		void remove_suffix(int n) {
			length_ -= n;
		}

		bool operator==(const StringPiece& x) const {
			return ((length_ == x.length_) &&
			        (memcmp(ptr_, x.ptr_, length_) == 0));
		}
		bool operator!=(const StringPiece& x) const {
			return !(*this == x);
		}

#define STRINGPIECE_BINARY_PREDICATE(cmp,auxcmp)                             \
		  bool operator cmp (const StringPiece& x) const {                           \
		    int r = memcmp(ptr_, x.ptr_, length_ < x.length_ ? length_ : x.length_); \
		    return ((r auxcmp 0) || ((r == 0) && (length_ cmp x.length_)));          \
		  }
		STRINGPIECE_BINARY_PREDICATE(< , <);
		STRINGPIECE_BINARY_PREDICATE(<= , <);
		STRINGPIECE_BINARY_PREDICATE(>= , >);
		STRINGPIECE_BINARY_PREDICATE(> , >);
#undef STRINGPIECE_BINARY_PREDICATE

		int compare(const StringPiece& x) const {
			int r = memcmp(ptr_, x.ptr_, length_ < x.length_ ? length_ : x.length_);
			if (r == 0) {
				if (length_ < x.length_) r = -1;
				else if (length_ > x.length_) r = + 1;
			}
			return r;
		}

		string as_string() const { // 好吧，漂亮，构造了一个string
			return string(data(), size());
		}

		void CopyToString(string* target) const {
			target->assign(ptr_, length_);
		}

#ifndef MUDUO_STD_STRING
		void CopyToStdString(std::string* target) const {
			target->assign(ptr_, length_);
		}
#endif

		  // Does "this" start with "x"
		bool starts_with(const StringPiece& x) const {
			return ((length_ >= x.length_) && (memcmp(ptr_, x.ptr_, x.length_) == 0));
		}
	};

}   // namespace muduo

// ------------------------------------------------------------------
// Functions used to create STL containers that use StringPiece
//  Remember that a StringPiece's lifetime had better be less than
//  that of the underlying string or char*.  If it is not, then you
//  cannot safely store a StringPiece into an STL container
// ------------------------------------------------------------------

#ifdef HAVE_TYPE_TRAITS
// This makes vector<StringPiece> really fast for some STL implementations
template<> struct __type_traits<muduo::StringPiece> {
	typedef __true_type    has_trivial_default_constructor;
	typedef __true_type    has_trivial_copy_constructor;
	typedef __true_type    has_trivial_assignment_operator;
	typedef __true_type    has_trivial_destructor;
	typedef __true_type    is_POD_type;
};
#endif

// allow StringPiece to be logged
std::ostream& operator<<(std::ostream& o, const muduo::StringPiece& piece);

#endif  // MUDUO_BASE_STRINGPIECE_H
